The broad goal of this project is to elucidate the molecular mechanisms of signal recognition and transduction by the mammalian MAS oncogene in regulating normal growth or malignant transformation.Based on expression and functional analysis in heterologous cells, MAS has been proposed to function as a specialized receptor for the angiotensin peptide family. The specific aims of this proposal are as follows: (1) The mechanism of malignant transformation of mammalian cells. Studies are to determine the capability of MAS alone or in the presence of agonist peptides to elicit cell transformation, to assess the transforming activity of MAS- related genes, RTA and MRG, and to determine the transforming properties of MAS mutant construct. (2) The molecular characterization of the MAS oncoprotein and its receptor-coupled transduction events. In this specific aim, the applicant intends to characterize MAS protein with special emphasis on the evidence for post-translational modification and to answer the question of whether MAS is a functional angiotensin receptor.